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United States Patent |
5,021,592
|
Beer
,   et al.
|
June 4, 1991
|
Redox-active centers
Abstract
A polymetallocene macrocycle which comprises a ring of alternating in-chain
aromatic residues and in-chain alkylene units and which bears four or more
transition metal complexes or metallocenyl groups. Such macrocycles are
redox-active hydrophobic host molecules potentially useful as electron
transfer mediators, for chemical sensor design, as redox catalysts or as
Second Harmonic Generator material.
Inventors:
|
Beer; Paul D. (Birmingham, GB2);
Tite; Elizabeth L. (Birmingham, GB2)
|
Assignee:
|
Imperial Chemical Industries PLC (London, GB2)
|
Appl. No.:
|
343342 |
Filed:
|
April 26, 1989 |
Foreign Application Priority Data
| Apr 26, 1988[GB] | 8809862 |
| Oct 05, 1988[GB] | 8823384 |
Current U.S. Class: |
556/1; 556/136; 556/138; 556/140 |
Intern'l Class: |
C07C 015/02; C07C 011/00; C07C 015/00 |
Field of Search: |
556/1,136,137,138,140,42
|
References Cited
U.S. Patent Documents
3644455 | Feb., 1972 | Onsager | 556/138.
|
4767873 | Aug., 1988 | Katz et al. | 556/42.
|
4888032 | Dec., 1989 | Busch | 556/138.
|
Primary Examiner: Prescott; Arthur C.
Attorney, Agent or Firm: Cushman, Darby & Cushman
Claims
We claim:
1. A polymetallocene macrocycle of the General Formula
##STR12##
wherein Z.sup.1 and .sup.2, which may be in the same as or different from
each other, may be hydrogen, hydrocarbyl, acyl, aroyl, alkylimino,
acylimino, metallocene-CO-- or metallocene-CH.sub.2 --, or Z.sup.1 and
Z.sup.2 on one aromatic group may together form a link between the 0's
thereof or Z.sup.1 on one aromatic group and Z.sup.2 on an adjacent
aromatic group may form an intramolecular link between the 0's on the two
said groups;
R.sup.1 and R.sup.2, which may be the same as or different from each other,
may be hydrogen, hydrocarbyl, acyl, aroyl, nitro, amino, hydroxyl,
carbonyl, carboxyl, etc or R.sup.2 may be ferrocenecarbonyloxy; and
Z.sup.3 is a hydrocarbyl group, a metallocene residue, or a heterocyclic
group or a transition metal complex thereof except that least one of
Z.sup.1, Z.sup.2 or Z.sup.3 bears a metallocene residue and/or Z.sup.3 is
a metal complex of the heterocyclic group wherein the metal in Z.sup.1,
Z.sup.2, or Z.sup.3 is a transition metal.
2. A polymetallocene macrocyle as claimed in claim 1 wherein the
metallocene residue is derived from a five-membered ring of the general
formula
##STR13##
wherein M is a transition metal.
3. A polymetallocene macrocycle as claimed in claim 1 wherein the
transition metal is iron.
4. A polymetallocene macrocycle as claimed in claim 1 wherein Z.sup.3 is a
metallocene residue.
5. A polymetallocene macrocycle as claimed in claim 1, wherein Z.sup.1 and
Z.sup.2 separately represent metallocene residues.
6. A polymetallocene macrocycle as claimed in claim 1 wherein Z.sup.1 and
Z.sup.2 on adjacent resorcinol residues together provide a bridge between
oxygen atoms on the two resorcinol residues.
7. A polymetallocene macrocycle as claimed in claim 6 wherein the bridge
comprises an alkylene unit and Z.sup.3 is a metallocene residue.
8. A polymetallocene macrocycle as claimed in claim 6 wherein the bridge
comprises a metallocene residue and Z.sup.3 is a hydrocarbyl group.
Description
This invention relates to macrocyclic products, particularly macrocyclic
products derived from metallocenes, more particularly where the
metallocene is ferrocene and to a process for the preparation thereof.
The design and synthesis of receptor molecules containing a redox-active
centre in close proximity to a crown-ether or cryptand coordination site
are known. It has now been recognised by the inventors that it would be
desirable to incorporate redox centres into hydrophobic host molecules to
produce a product which would allow (i) interactions between the
redox-active moiety and an included organic substrate to be detected and
(ii) potential catalytic interactions to be investigated.
We have now prepared redox-active hydrophobic host molecules comprising a
ring of alternating in-chain aromatic residues and in-chain alkylene units
which ring bears four or more transition metal complexes or so-called
metallocenyl groups.
According to the present invention there is provided a polymetallocene
macrocycle of the General Formula I
##STR1##
wherein Z.sup.1 and Z.sup.2, which may be the same as or diffferent from
each other, may be hydrogen, hydrocarbyl, acyl, aroyl, alkylimino,
acylimino, metallocene-CO--, or metallocene-CH.sub.2 --, or Z.sup.1 and
Z.sup.2, on one aromatic group may together form a link between the 0's
thereof or a Z.sup.1 on one aromatic group and Z.sup.2 on an adjacent
aromatic group may form an intramolecular link R.sup.1 and R.sup.2, which
may be the same as or different from each other, may be hydrogen,
hydrocarbyl, acyl, aroyl, nitro, amino, hydroxyl, carbonyl, carboxyl, etc
or R.sup.2 may be ferrocenecarbonyloxy ; and Z.sup.3 is a hydrocarbyl
group, a heterocyclic group, a metallocene residue or a transition metal
complex of the heterocyclic group; except that at least one of Z.sup.1,
Z.sup.2, or Z.sup.3 bears a metallocene residue and/or Z.sup.3 is a
complex of a heterocyclic group wherein the metal in Z.sup.1, Z.sup.2 or
Z.sup.3 is a transition metal.
In the General Formula I, Z.sup.1 and Z.sup.2 are preferably acyl groups or
metallocene carbonyl residues. Where Z.sup.1 and Z.sup.2 are acyl groups,
preferably they are aroyl groups, more preferably benzoyl to give a
product with preferable solubility.
In the General Formula I, where R.sup.1 is not hydrogen, R.sup.2,
preferably is hydrogen for steric considerations.
The metallocene residue present in General
Formula I, is preferably derived from a five membered ring of the General
Formula II
##STR2##
where M is a transition meta 1. However, we do not exlcude the
possibility that is could be derived from one or more rings of different
sizes, e.g. six- or seven-membered rings, such that the metallocene
residues present in compounds of the General Formula I may have a
structure represented by, for example, General Formulae III a, b, c,
##STR3##
Where M has the meaning hereinbefore ascribed to it.
Where the aforementioned metallocene residue bears a positive charge, e.g.
as in General Formula IIIa, the anion associated therewith will be readily
chosen by the man skilled in the art; typically it is a halide or PF.sub.6
--.
In the General Formula I, where Z.sup.3 is a hydrocarbyl group it is
preferably an alkyl group having at least five C atoms to improve
solubility. We have found that such a group tends to improve the
solubility of the polymetallocene macrocycle, although we do not exclude
the possibility that it may be an alternative hydrocarbyl, for example an
aryl group, e.g. phenyl.
As examples of the heterocyclic group Z.sup.3 in the General Formula I,
where Z.sup.3 is a heterocyclic group, may be mentioned inter alia cyclic
ethers, e.g.
##STR4##
or, a pyridyl or a bipyrdidyl, e.g.,
##STR5##
residue.
It will be appreciated that where Z.sup.3 is a certain heterocyclic group,
e.g. a pyridyl, or particularly the aforementioned bipyridyl, the compound
of General Formula I may be reacted with a transition metal complex such
that Z.sup.3 is converted into a metal-containing residue, e.g.
##STR6##
Furthermore, where Z.sup.1 and/or Z.sup.2 in a compound of General Formula
I is a metallocene residue bearing a first metal, e.g.
##STR7##
and Z.sup.3 is a second metal-containing residue, e.g. of General Formula
IV, it will be appreciated that compounds of the General Formula I may
provide different redox-active centres at Z.sup.1 /Z.sup.2 from Z.sup.3.
As examples of the transition metal M from which the metallocene derivative
is derived, where Z.sup.1, Z.sup.2 or Z.sup.3 is a metallocene residue in
compounds of General Formula I or the metal complex is derived, where
Z.sup.3 is a transition metal complex of a heterocyclic compound in
compounds of the General Formula I, may be mentioned inter alia Mo, W or
preferably a metal of Group VIII of the Periodic Table, particularly
preferably ruthenium, cobalt or iron or more particularly preferably iron.
It will be appreciated that the presence of a substituent at the position
ortho to both the OZ.sup.1 and OZ.sup.2 groups on an aromatic ring in
General Formula I may well hinder or prevent the formation of an
intramolecular link between those groups.
According to a further aspect of the present invention there is provided a
process for the preparation of a polymetallocene macrocycle which process
comprises at least the steps of:
A. reacting a resorcinol with a carboxaldehyde;
B. reacting the product of step A with
(i) a carboxylic acid, or a suitable derivative thereof, under conditions
such that substantially all of the hydroxyl groups in the product from
Step A are converted into ester groups; or
(ii) with an ether-forming halo-derivative under conditions such that
substantially all of the hydroxyl groups in the product from Step A are
converted into ether groups;
with the proviso that a metallocene derivative is used in at least one of
the said steps, preferably in Step A.
It will be appreciated that the resorcinol used therein will have at least
both the 2- and 4-positions unsubstituted. The resorcinol may bear a
substituent, eg an alkyl, aryl, hydroxyl, carboxyl or nitro group, on the
carbon atom ortho to both hydroxyl groups, ie R.sup.1, which does not
unduly inhibit the process of the present invention. However, where
R.sup.2 is not hydrogen, R.sup.1 preferably is hydrogen.
The metallocenecarboxaldehyde used in Step A of the process according to
the present invention may be prepared by methods known in the art, e.g. K
Schogl, Monatsch. Chem., 1957, 88, 60.
Step A in the process of the present invention is preferably carried out in
a polar organic solvent, more preferably ethanol, in the presence of a
suitable acidic catalyst, preferably hydrochloric acid, e.g. about 10M
HCl. The product of Step A, where ferrocene carboxaldehyde is the
metallocene carboxaldehyde which is reacted with resorcinol, has the
structure represented by General Formula V
##STR8##
In Step B of the process according to the present invention, the product of
Step A, ie a compound of the General Formula I wherein Z.sup.1 and Z.sup.2
are hydrogen, e.g. V, is preferably reacted with an acid chloride,
although we do not exclude the possibility that an alternative
ester-forming acid derivative, e.g. an anhydride, may be used.
Preferably the product of Step A is benzoylated such that a product of
desired solubility is obtained, or treated with a metallocene carbonyl
chloride, e.g. ferrocenecarbonyl chloride to afford a novel product of
desired solubility. Step B is preferably carried out in suspension in a
suitable liquid, e.g. tetrahydrofuran. Where ferrocenecarbonyl chloride
and a product of the General Formula V are used in Step B the product has
the structure shown in General Formula VI
##STR9##
Where a 1,1-bis (chlorocarbonyl)-Ferrococene and a product of the General
Formula V are used in Step B a product of General Formula VII is obtained.
##STR10##
As examples of ether-forming halo-derivatives which may be reacted in Step
B with the product from Step A may be mentioned inter alia aralkyl
halides, e.g. benzyl bromide, metallocenyl halides, and alkylene
dihalides, e.g. bromochloromethane. The preparation of an ether according
to the present invention may be effected by reacting the aforesaid
halo-derivatives with a compound of the General Formula I, where Z.sup.1
and Z.sup.2 represent hydrogen, under conditions known in the art, e.g.
using sodium carbonate as catalyst.
Where an ether forming dihaloalkane is used in Step B the product often has
the structure shown in General Formula VIII.
##STR11##
wherein m is typically 1-6 and preferably 1.
The macrocyclic compound according to the present invention comprises a
transition metal it may be used as an electron transfer mediator, for
chemical sensor design, as a redox catalyst or as a Second Harmonic
Generator (SHG) material.
The present invention is further illustrated by reference to the following
Examples.
EXAMPLE 1
This Example illustrates a compound according to the present invention,
containing four redox-active centres.
Concentrated hydrochloric acid (6 ml) was rapidly added to a homogeneous
solution of resorcinol (3.19 g, 29 mmol) and ferrocenecarboxaldehyde (6.19
g, 29 mmol) in ethanol (30 ml). The reaction mixture was stirred at about
75.degree. C. for 4 hours and then cooled to 0.degree. C. The compound
having the General Formula V formed as a black precipitate; it was
filtered off and washed with water until the washings were no longer
acidic. The black precipitate was dried in vacuo.
The black precipitate was insoluble in substantialy all common solvents
including base. It was too involatile for analysis by mass spectrometry.
The infra-red spectrum revealed a large hydrogen-bonding peak between 3700
and 2700cm.sup.-1. It had a melting point above 250.degree. C.
EXAMPLE 2
This Example illustrates a compound according to the present invention,
wherein the aromatic rings bear ester groups.
Triethylamine (2 ml) and then an excess of benzoyl chloride (2.8 g) were
added to a suspension of the black precipitate, prepared in Example 1 in
dried tetrahydrofuran. The resulting mixture was refluxed for four days,
cooled, evaporated to dryness, washed with base and water and the product
thereform was purified by column chromatography down an alumina column
with diethyl ether/dichloromethane in ratio 75:25 as the eluent. The
compound of General Formula I (wherein both Z.sup.1 and Z.sup.2 represent
PhCO, R.sup.1 and R.sup.2 represent hydrogen and Z.sup.3 represents
ferrocene) was obtained as orange crystals.
Analysis of the orange crystals revealed the following data:
.sup.1 H nmr (CDCl.sub.3) signals at: 3.93 (24H,s) 4.05 (4H,s), 4.12
(4H,s), 4.23 (4H,s), 5.65 (4H,s), 6.64 (2H,s), 6.73 (2H,s), 6.75 (2H,s)
7.20, 7.25 (8H,m), 7.42-7.58 (16H,m), 7.8-7.99 (16H,m).
.sup.13 C nmr (CDCl.sub.3) signals at: 164.70, 163.30, 14 7 17, 145.57,
133.90, 133.14, 131.15, 130.35, 129.88, 128.24, 116.47, 114.82, 89.94,
77.21, 76.90, 76.58, 69.06, 68.51, 67.98, 67.09 32.20.
The infra-red spectrum (KBr disc) of the orange crystals had a peak at 1735
cm.sup.-1 (C=0). Mass spectroscopy of the orange crystals indicated
M/Z=2057 and they were found to have a melting point above 250.degree. C.
(decomposition).
Electrochemical experiments (acetonitrile, SCE) revealed two, two electron
reversible oxidation waves at +0.575 v and +0.665 v corresponding to the
oxidation of the respective four ferrocenyl moieties.
EXAMPLE 3
This Example illustrates a further compound according to the present
invention, containing twelve redox.active centres.
The procedure of Example 2 was repeated except that an excess of
ferrocenecarbonyl chloride was used instead of benzoyl chloride.
The ferrocenecarbonyl chloride was prepared by the process described by
Falk, Krasa and Schlogel in Monatschefte fur Chemie, 1969, 100, 152.
The structure of the product was confirmed as that of a compound of General
Formula VI by the following analysis which revealed the following data:
.sup.1 H nmr (CDCl.sub.3): signals at 4.06, 4.19, 4.38, 4.82 (108H,
4.times.s), 5.48 (4H,s), 6.72 (4H,s) and 7.26 (CHCl.sub.3); infra-red (KBr
disc): peak at 1720 cm.sup.-1 (C=0); mass spectroscopy: M/Z 2921; and
melting point above 250.degree. C.
EXAMPLE 4
This Example illustrates a further compound according to the present
invention wherein there are intra-molecular alkylene bridges.
A portion (6.12 gms, 5 mmol) of the di-hydroxy compound prepared in Example
1, anhydrous potassium carbonate (8 gms, 58 mmol) and bromochloromethane
(4 gms, 31 mmol) in dried dimethylformamide (150 mls) were stirred at
about 85.degree. C. in a nitrogen atmosphere for 68 hours. The solvent was
evaporated under reduced pressure and the brown residue was triturated
with dichloromethane. The mixture was filtered through a bed of Celite,
the eluate was dried over magnesium sulphate and evaporated at reduced
pressure. The residual brown solid was chromatographed on an alumina
column with CH.sub.2 Cl.sub.2 as the eluent. Slow evaporation of the
eluent gave orange crystals (0.08 g, 1% yield) of the General Formula VIII
wherein m is 1.
Analysis of the product gave the following data: .sup.1 H nmr (CDCl.sub.3)
signals at: 3.75 (20H,s), 4.28 (8H,s), 4.42 (8H,s), 4.50, 4.53 (4H,
2.times.s), 5.30 (CH.sub.2 Cl.sub.2), 5.83, 5.86 (4H, 2.times.s). 5.96
(8H,s) 6.55 (4H,s), 7.26 (CHCl.sub.3) and 7.64 (4H,s);
.sup.13,C nmr (CDCl.sub.3) signals at 38.87, 68.32, 68.19, 70.49, 75.60,
76.35, 77.00, 78.43, 79.57, 87.88, 99.69, 115.89, 125.09, 138.87 and
153.86; Mass spectroscopy: M/Z 1272; and melting point above 250.degree.
C.
EXAMPLE 5
This Example illustrates a yet further compound according to the present
invention, bearing eight ferrocene residues.
First Stage
Concentrated hydrochloric acid (10 mls) was added dropwise to a stirred
solution of resorcinol (11 g, 0.1 mol) and acetaldehyde (4.41 g, 0.1 mol)
in distilled water (40 mls). A cream precipitate rapidly formed. The
reaction mixture was stirred at 75.degree. C. for one hour, then cooled in
a freezer. The cream precipitate was then filtered off, washed with water
until the washings were no longer acidic, and dried under vacuum.
Second Stage
Ferrocene carbonyl chloride (0.74 g, 3.times.10.sup.-3 mol; prepared as
described in Example 3), triethylamine (0.6 mls, 4.times.10.sup.-3 mols)
and dimethylamino pyridine (catalytic amount, 0.03 g) were stirred under
nitrogen at room temperature in dried tetrahydrofuran (75 mls). A portion
(0.081 g, 1.5.times.10.sup.-4 mols) of the product from the first stage in
dried tetrahydrofuran (75 mls) was added to the above reaction mixture. It
was heated at reflux for 2 hours and then rotary evaporated. The residue
from the rotary evaporator was dissolved in dichloromethane. This solution
was washed with water, and the organic layer was dried with magnesium
sulphate. The product was purified by column chromatography down an
alumina column. The material eluted with dichloromethane was discarded,
and the material eluted with dichloromethane/methanol (99 75:0.25% v/v)
was collected and recrystallised from dichloromethane/methanol to yield
orange crystals (overall yield 33%) of the General Formula I wherein
Z.sup.1 =Z.sup.3 =ferrocenecarbonyl and Z.sup.3 is methyl. following
properties; Nuclear magnetic resonance revealed signals at
.sup.1 H nmr (CDCl.sub.3) (16H,s), 4.62, 4.64, 4.66, 4.68 (4H,q); 4.71
(4H,s), 4.76 (4H,s), 4.83 (4H,s), 4.94 (4H,s) 5.29 (CH.sub.2 Cl.sub.2),
6.34 (2H,s), 7.06 (2H,s), 7.14 (2H,s) 7.25 (CHCl.sub.3), 7.65 (2H,s); and
Nuclear magnetic resonance revealed signals at: .sup.13 C nmr (CDCl.sub.3):
20.58, 69.83, 70.39, 71.58, 71.65, 76.58, 76.76, 78.81, 76.90, 77.10,
77.22, 115 56, 116.41, 125.87, 132.51, 135.83, 145.88, 147.89, 169.18,
169.68, 207.09;
The infra-red spectrum (KBr disc) had a peak at 1730 cm.sup.-1 (C=0). Mass
spectroscopy revealed, M/Z=2241 and it was found to have a melting point
greater than 250.degree. C. (decomposition).
EXAMPLE 6
This Example illustrates a yet further compound according to the invention
wherein there are intramolecular metallocene bridges.
A portion of the dihydroxy compound prepared from the reaction of
resorcinol and acetaldehyde by the method of Hogberg (Journal of Organic
Chemistry, 1980, Vol 45, 4498) i.e. a compound of the General Formula I
wherein Z.sup.1 =Z.sup.2 =H and Z.sup.3 =CH.sub.3) was treated with an
excess of 1,1'-bis-chlorocarbonyl-ferrocene (prepared by the method of
Lorkowski, Pannier and Wende, J Prakt. Chem. 1967, 35,149) under the
conditions described in Example 2.
The product was obtained as an orange crystalline solid. The structure
thereof was confirmed by chemical analysis, mass spectrometry and .sup.1 H
and .sup.13 C nmr spectroscopy, as an intra-molecular bridged compound of
General Formula VII wherein Z.sup.3 is CH.sub.3.
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